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Finding the Fourth Proportional to 285.90, 396.20 and 280.43

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Solution

The fourth proportional to 285.90, 396.20 and 280.43 is: 388.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.90 : 396.20 = 280.43 : x
  2. Step 2: Convert to fraction form
    285.90/396.20 = 280.43/x
  3. Step 3: Cross multiply
    285.90x = 396.20 × 280.43
  4. Step 4: Simplify right side
    285.90x = 111,102.98
  5. Step 5: Solve for x
    x = 111,102.98/285.90
  6. Step 6: Final answer
    x = 388.61

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.